This invention relates to an impact flowmeter. More particularly, the present invention relates to an impact flowmeter which provides increased accuracy and reliability compared to conventional impact flowmeters.
It is known to provide an impact flowmeter situated in a flow conduit to determine the flow rate of bulk material through the conduit. Known impact flowmeters include an impact plate located in a flow stream so that bulk material passing through the flowmeter strikes the impact plate. A load cell is typically coupled to the impact plate to provide an output signal proportional to the flow rate of the bulk material through the conduit. The output signal from the load cell can be processed to determine the mass flow rate of the bulk material through the conduit.
The present invention is an improvement over conventional impact flowmeters. The present invention provides an accurate, reliable design which is relatively inexpensive to manufacture and easy to install. The present invention provides a low cost impact flowmeter for measuring continuous flow of most bulk solids. The impact flowmeter of the present invention is designed to fit into existing processes and provides an economical alternative to some loss-in-weight in volumetric batching systems. The flowmeter can be used with most mechanical conveying systems including belt conveyors, air slides, rotary valves, drag conveyors, screw conveyors, and vibratory conveyors. Typical applications for the impact flowmeter of the present invention include flow rate control, batching, loading and mix ratio control. Typical industries which may be served by the present invention include mining, chemical, plastics, food, grain and animal feed.
One problem associated with conventional impact flowmeters is that the impact flowmeters become inaccurate due to ambient system vibration or due to vibration caused by the bulk material flowing through the impact flowmeter. Another problem associated with conventional flowmeters is that temperature extremes, dust, and material build-up on the load cell itself can cause inaccuracies. This build-up problem becomes worse when corrosive or abrasive materials are processed.
One object of the present invention is to reduce the effect of vibration on the accuracy of the output of the load cell.
Another object of the present invention is to isolate the load cell from the process environment within a housing of the impact flowmeter to protect the load cell from process temperature extremes, dust, and material built-up on the load cell.
Yet another object of the present invention is to provide means for adjusting the position of the load cell and impact plate relative to the housing so that the impact plate is optimally positioned relative to a material inlet chute to provide proper bulk solid material impact with the impact plate.
According to one aspect of the present invention, an impact flowmeter includes a housing having an inlet end, an outlet end, and an interior region. The flowmeter also includes an inlet chute coupled to the inlet end of the housing. The inlet chute has an open end for discharging material into the interior region of the housing. The flowmeter further includes a load cell coupled to the housing for generating an output signal, and an impact plate coupled to the load cell. The impact plate is aligned with the inlet chute so that material entering the housing strikes the impact plate. The impact plate deflects the load cell in a measurement direction to change the output signal from the load cell based on the flow rate of material. The flowmeter still further includes means for biasing the load cell in the measurement direction to establish a preload condition on the load cell, thereby reducing the affect of vibration on the output signal from the load cell.
In the illustrated embodiment, the load cell is coupled to the housing by a load cell mounting bracket. The biasing means includes a stop coupled to the load cell mounting bracket. The position of the stop is adjustable relative to the load cell to apply a biasing force to the load cell in the measurement direction.
According to another aspect of the invention, an impact flowmeter includes a housing having an inlet end, an outlet, and an interior region. The flowmeter also includes an inlet chute coupled to the inlet end of the housing. The inlet chute has an open end for discharging material into the interior region of the housing. The flowmeter further includes a load cell and a load cell mounting bracket located outside the interior region of housing to isolate the load cell from the interior region of the housing. The load cell mounting bracket is coupled to a wall of the housing and to the load cell to secure the load cell to the housing. The flowmeter still further includes an impact plate and means for coupling the impact plate to the load cell to align the impact plate with the inlet chute so that material entering the interior region of the housing strikes the impact plate.
According to yet another aspect of the present invention, an impact flowmeter includes a housing having an inlet end, an outlet end, and an interior region. The flowmeter also includes an inlet chute coupled to the inlet end of the housing. The inlet chute has an open end for discharging material into the interior region of the housing. The flowmeter further includes a load cell for generating an output signal, and means for coupling the load cell to a wall of the housing. The flowmeter still further includes an impact plate coupled to the load cell to align the impact plate with the inlet chute so that material entering the interior region of the housing strikes the impact plate to change the output signal from the load cell. In addition, the flowmeter includes means for insulating the load cell from the housing to reduce the effect of ambient vibrations of the housing on the load cell. In the illustrated embodiment, the insulating means includes a gasket located between the load cell coupling means and the housing.
According to still another aspect of the present invention, an impact flowmeter includes a housing having an inlet end, an outlet end, and an interior region. The flowmeter also includes an inlet chute coupled to the inlet end of the housing. The inlet chute has an open end for discharging material into the interior region of the housing. The flowmeter further includes a load cell coupled to the housing for generating an output signal, and an impact plate coupled to the load cell. The impact plate is aligned with the inlet chute so that material entering the housing strikes the impact plate. The impact plate deflects the load cell in a measurement direction to change the output signal from the load cell based on the flow rate of material. The flowmeter still further includes means for adjusting the position of the impact plate vertically and horizontally relative to the inlet chute.
In the illustrated embodiment, the flowmeter includes means for coupling the load cell to the housing so that the position of the load cell relative to the housing is adjustable to change the position of the impact plate relative to the inlet chute. In addition, the flowmeter includes means for coupling the impact plate to the load cell so that the position of the impact plate relative to the load cell is also adjustable to change the position of the impact plate relative to the inlet chute.
The impact plate is coupled to the load cell by an impact plate mounting bracket coupled to a measurement leg of the load cell. The impact plate mounting bracket is formed to include an elongated slot therein. The load cell is coupled to the impact plate mounting bracket by two fasteners extending through the elongated slot to permit the impact plate mounting bracket to slide relative to the load cell to adjust the position of the impact plate relative to the load cell and inlet chute.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.